Wikipedia
' Mitchigamea' or Michigamea or Michigamie were a tribe in the Illinois Confederation. Not much is known about them and their origin is uncertain. Originally they were said to be from Lake Michigan, perhaps the Chicago area. Mitchie Precinct, Monroe County in Southwestern Illinois takes its name from their transient presence nearby, north of the French Fort de Chartres in the American Bottom along the Mississippi. One of their villages in the American Bottom, inhabited from 1730 until 1752, is one of the region's premier archaeological sites; it is known as the " Kolmer Site".
It is suggested that the people later moved to Arkansas under pressure from the Iroquois. Their best-known chief was Agapit Chicagou.
The Jesuit Relations say: "At 5 miles from the village, I found the Tamaroa, who have taken up their winter quarters in a fine Bay, where they await the Mitchigamea, -- who are to come more than 60 leagues to winter there, and to form but one village with them."
In 1673, Jacques Marquette and Louis Jolliet used a Mitchigamea man, who only spoke Illinois poorly, as a translator between the Illinois-speaking French, and the Siouan-speaking Quapaw. Jean Bernard Bossu provides two sentences from the mid-18th century which, according to John Koontz, indicate that Michigamea was a Siouan language of the Mississippi branch.